1. FIELD OF THE INVENTION
This invention is directed toward an improved tree felling head.
The invention is more particularly directed toward an improved tree felling head of the type employing a rotatable, swingable cutting bar.
2. DESCRIPTION OF THE PRIOR ART
Tree felling heads employing rotatable, swingable, cutting bars are well known. Examples of such felling heads are shown in Canadian Patents Nos. 960,549; 1,006,419 and 1,061,680. In all the above patents, the cutting bar is supported at its ends in a carrying frame which in turn is pivotally supported at one end on a felling head frame. The carrying frame, carrying the rotating cutting bar, is swung in a cantilevered manner to swing the cutting bar against a tree to have the bar cut through it.
Using a swingable cutting bar to fell trees has several advantages. The cutting bar, its drive means, and its support are all quite light making for a lighter and more maneuverable felling head. Less power is required to cut the trees and the cutting bar gives a clean cut. However the swingable, cantilevered cutting bars are not too strong. The weight of a cut tree resting on the carrying frame results in large bending forces on the frame and its cantilever mounting. Frequent maintenance is required and breakdowns often occur in these felling heads. Also, known felling heads employing cutting bars have binding pro legs. The chips and sawdust produced by the bars during cutting are often difficult to clear from the cut and binding can occur. Further all of the known felling heads employing swingable cutting bars have no known accumulating capabilities. Thus any tree harvesting operation employing these felling heads is a slow operation, since the felling head can only handle one tree at a time.
It is also known to provide tree felling heads employing rotatable, slidable, cutting bars. Examples of such felling heads are shown in U.S. Pat. Nos. 4,153,086 and 4,540,033. These felling heads have an advantage over the felling heads using swingable, cantilevered cutting bars in that the carrying frame supporting their cutting bars can be securely supported at both ends. Thus these felling heads are much stronger and require less maintenance. Also, as shown in U.S. Pat. No. 4,540,033, the felling head employing a slidable cutting bar can be used with accumulating means. Thus this felling head is more productive in harvesting trees. However, slidable bar felling heads are quite large in size compared to swingable bar felling heads and thus are cumbersome and awkward to handle in the bush.